The reliability of the rhesus monkey as an important experimental animal depends on its genetic concordance with human. During our assessment of the rhesus monkey as a preclinical model for coagulation-related research, we cloned the full-length cDNA of rhesus monkey factor X (FX) and compared its genetic characteristics and coagulation activity with those of human FX. The full-length cDNA of rhesus monkey FX was 1683 bp in length, corresponding to 487 coding amino acids and sharing 94.71% nucleotide identity and 93.65% amino acid identity with human FX. When FX sequences from different animals were compared with that of human FX, rhesus monkey and baboon FX showed similar degrees of homology to human FX, which were less than that between human and chimpanzee FX sequences but remarkably higher than those of another 2 monkey species, bovine, pig, and rodents. Comparison of functional sites between human and rhesus monkey FX revealed high similarities between their amino acids sequences and 3-dimensional structures. The average coagulation activity of FX from 24 rhesus monkeys was in the normal range of that of healthy humans. The rhesus monkey therefore may be a suitable animal model for research addressing coagulation factor X.